The applicant wll continue his studies of the regulatory role of adenosine 3',5'-monophosphate (cyclic AMP). Specfically, he will examine its function in the development of the cellular slime mold Dictyostelium discoideum. Emphasis in this investigation will be on the following aspects of the problem: 1. The relationship between starvation and the oscillatory increases in intracellular and extracellular cyclic AMP. 2. The mechanisms by which intracellular cyclic AMP triggers the anabolic and catabolic reactions which constitute development in D. discoideum. 3. The isolation of developmental mutants in which development occurs even in the presence of nutrients. 4. The isolation of pre-spore and pre-stalk amebae and the determination of cyclic AMP concentrations in the two cell types.